Spatial light modulators (SLMs) are transducers that modulate an incident beam of light in a spatial pattern in response to an optical or electrical input. The incident light beam may be modulated in phase, intensity, polarization, or direction. This modulation may be accomplished through the use of a variety of materials exhibiting magneto-optic, electro-optic, or elastic properties. SLMs have many applications, including optical information processing, display systems, and electrostatic printing.
The present invention relates to SLMs having reflective micromirrors that are provided within a micromirror array for, e.g., projection-type displays (or for steering light beams, maskless lithography and maskless micro array production). A simplified such display system is illustrated in FIG. 1. In its very basic configuration, display system 100 comprises light source 102, optical devices (e.g. light pipe 104, condensing lens 106 and projection lens 108), display target 112 and spatial light modulator 110 that further comprises a plurality of micromirror devices (e.g. an array of micromirror devices). Light source 102 (e.g. an arc lamp) emits light through the light integrator/pipe 104 and condensing lens 106 and onto spatial light modulator 110. The micromirrors of the spatial light modulator 110 are selectively actuated by a controller (e.g. as disclosed in U.S. Pat. No. 6,388,661 issued May 14, 2002 incorporated herein by reference) so as to reflect—when in their “ON” position—the incident light into projection optics 108, resulting in an image on display target 112 (screen, a viewer's eyes, a photosensitive material, etc.). Generally, more complex optical systems, such as systems employing more than three spatial light modulators (each being designated for modulating one of the three primary colors—red, green, and red) are often used, especially in displaying applications for color images.
Currently, varieties of MEMS-based SLMs for use in display systems have been developed. Regardless of the differences, a common basic configuration of the MEMS-based SLMs comprises a hinge and a micromirror plate that is attached to the hinge for rotating relative to the substrate by the hinge. And the mechanism of the MEMS-based SLMs for display is based on rotating the micromirror plate of individual micromirrors along the hinge at different angles, thus reflecting incident light onto or away from a display target at the different angles. In this regard, mechanical properties of the hinge, the micromirror plate and the attachment of the two are critical factors to the overall performance of the micromirrors and the quality of the displayed images.
Therefore, what is needed is a spatial light modulator having micromirrors devices with robust mechanical properties for use in display systems.